A group of Amazon employees voted against forming what would’ve been the company’s first-ever U.S. labor union Wednesday evening, per Businessweek.

The vote was set up last month after workers at an Amazon fulfillment center in Middletown, Del. were reportedly upset over frequently-shifting managers and a lack of opportunities for promotion.

The union would’ve been part of the International Association of Machinists and Aerospace Workers. IAMAW spokesperson John Carr told Businessweek the vote failed 21-6 because of “intense pressures” from Amazon, which fought the unionization efforts.

“That number is a clear reflection that the tactics Amazon and their law firm employed were very effective,” said Carr.

Amazon spokesperson Mary Osako, meanwhile, told Businessweek that “our employees have made it clear that they prefer a direct connection with Amazon.”

“This direct connection is the most effective way to understand and respond to the wants and needs of our employees. Amazon’s culture and business model are based on rapid innovation, flexibility and open lines of direct communication between managers and associates.”